Cognitive change following MPTP exposure.
In a previous study, we demonstrated that patients with MPTP-induced parkinsonism (MPTP-IP) had a pattern of cognitive change similar to that in nondemented patients with idiopathic Parkinson's disease (PD). The present study addressed cognitive change in MPTP-exposed but relatively asymptomatic (MPTP-AS) individuals. We examined them for general intellectual function, construction, language, memory, executive function, attention, and reaction time, and compared their performance with data obtained in the previous study from patients with MPTP-IP and drug addict controls. Each MPTP-AS individual had some subtle parkinsonian signs, but in no case would these be sufficient for a diagnosis of PD. PET studies showed that these individuals had significantly reduced uptake of labeled 6-fluorodopa into the striatum. MPTP-AS and MPTP-IP groups performed comparably and were significantly worse than controls on tests of construction and category naming. The MPTP-AS group performed at a level between the other 2 groups on a test of executive function. The 3 groups performed comparably on all other measures. The similarity of the pattern of intellectual change in MPTP-AS to that seen in MPTP-IP and idiopathic PD supports the idea that the dopamine system mediates a specific set of cognitive functions and suggests that cognitive change can occur in the presence of few or no motor signs of parkinsonism.
Stern
Y
Y
Department of Neurology, Columbia University College of Physicians and Surgeons, New York, NY.
Tetrud
J W
JW
Martin
W R
WR
Kutner
S J
SJ
Langston
J W
JW
D015632:1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine / Q000009:adverse effects*; D000328:Adult; D003071:Cognition / Q000187:drug effects*; D006801:Humans; D009483:Neuropsychological Tests; D010302:Parkinson Disease, Secondary / Q000139:chemically induced* / Q000000981:diagnostic imaging / Q000503:physiopathology; D014055:Tomography, Emission-Computed
D015632:1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine